U.S. patent number 6,145,791 [Application Number 09/059,725] was granted by the patent office on 2000-11-14 for elastomeric transition for aircraft control surface.
This patent grant is currently assigned to Northrop Grumman Corporation. Invention is credited to Joseph B. Diller, Nicholas F. Miller, Jr..
United States Patent |
6,145,791 |
Diller , et al. |
November 14, 2000 |
Elastomeric transition for aircraft control surface
Abstract
Elastomeric transition sections (118, 124) are mounted between
the upper and lower portions of a wing (100) and a control surface
(102) hinged thereto. The elastomeric transition sections include
elastomeric material (126) having a plurality of holes (128) formed
therethrough. Flexible rods (134, 136) are secured to either the
wing or the control surface and extend through the holes (128) in
the elastomeric material (126). The elastomeric transition sections
provide a smooth aerodynamic transition between the wing and the
control surface while permitting the control surface to pivot about
the hinge axis (108) to perform the control function.
Inventors: |
Diller; Joseph B. (Hurst,
TX), Miller, Jr.; Nicholas F. (St. Charles, MO) |
Assignee: |
Northrop Grumman Corporation
(Los Angeles, CA)
|
Family
ID: |
22024851 |
Appl.
No.: |
09/059,725 |
Filed: |
January 9, 1998 |
Current U.S.
Class: |
244/215; 244/130;
244/219 |
Current CPC
Class: |
B64C
3/48 (20130101); B64C 9/02 (20130101) |
Current International
Class: |
B64C
9/02 (20060101); B64C 3/00 (20060101); B64C
3/48 (20060101); B64C 9/00 (20060101); B64C
003/52 () |
Field of
Search: |
;244/213-215,219,75R,130 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Barefoot; Galen L.
Attorney, Agent or Firm: Anderson; Terry J. Hoch, Jr.; Karl
J.
Claims
What is claimed is:
1. An aircraft wing assembly, comprising:
a main wing portion;
a control surface having a forward end, an inboard edge and an
outboard edge, the forward end being attached to the main wing
portion for movement of the control surface relative to the main
wing portion; and
a single elastomeric transition section joining the main wing
portion to the forward end, the inboard edge and the outboard edge
of the control surface, for mitigating aerodynamic discontinuities
occurring therebetween.
2. The aircraft wing assembly of claim 1 wherein:
the main wing portion has top and bottom portions;
the control surface has top and bottom portions; and
the elastomeric transition section joins the top portion of the
main wing portion to the top portion of the control surface, and
joins the bottom portion of the main wing portion to the bottom
portion of the control surface.
3. The aircraft wing assembly of claim 2 wherein:
the elastomeric transition section has upper and lower elastomeric
transition sections;
the upper elastomeric transition section joins the top portion of
the main wing portion to the top portion of the control surface;
and
the lower elastomer transition section joins the bottom portion of
the main wing portion to the bottom portion of the control
surface.
4. The aircraft wing assembly of claim,1 wherein the elastomeric
transition section has a plurality of rods extending therethrough
for structurally supporting the elastomeric transition section.
5. The aircraft wing assembly of claim 4 wherein selected ones of
the rods are attached to the main wing portion.
6. The aircraft wing assembly of claim 4 wherein selected ones of
the rods are attached to the control surface.
7. An aircraft wing assembly, comprising:
a main wing portion having top and bottom portions;
a control surface having top and bottom portions and a forward end,
the forward end being attached to the main wing portion for
movement of the control surface relative to the main wing portion;
and
a single elastomeric transition section joins the top portion of
the main wing portion to the top portion of the control surface at
forward end, and joins the bottom portion of the main wing portion
to the bottom top portion of the control surface at the forward
end, for mitigating aerodynamic discontinuities occurring
therebetween.
8. The aircraft wing assembly of claim 1 wherein the control
surface further includes inboard and outboard edges, and the
elastomeric transition section joins the top portion of the main
wing portion to the top portion of the control surface at the
inboard edge, and joins the bottom portion of the main wing portion
to the bottom portion of the control surface at the inbord
edge.
9. The aircraft wing assembly of claim 7 wherein the elastomeric
transition section having a plurality of rods extending
therethrough, for structurally supporting the elastomeric
transition section.
10. The aircraft wing assembly of claim 9 wherein selected ones of
the rods are attached to the main wing portion.
11. The aircraft wing assembly of claim 9 wherein selected ones of
the rods are attached to the control surface.
Description
TECHNICAL FIELD OF THE INVENTION
This invention relates to an aircraft control surface. More
specifically, this invention relates to an elastomeric transition
between a wing member and a control surface at the hinge connection
therebetween.
BACKGROUND OF THE INVENTION
The typical wing design for an aircraft includes a primary wing
surface, having a leading edge and a trailing edge, with a control
surface located on the leading and trailing edges of the wing.
Flaps and ailerons are both examples of control surfaces, with
flaps being designed to increase wing lift and ailerons used for
roll axis control. The flaps on each wing operate in unison to
increase wing lift by increasing the camber of the wing. By
comparison, ailerons are pivoted oppositely to increase lift on one
wing while reducing lift on the opposite wing to induce a rolling
moment. Similarly, the elevator sections of the horizon tail are
pivotably attached to the fixed tail section to vary lift and
provide pitch control.
When either the flap or the aileron is activated, the control
surface rotates relative to the trailing edge of the wing. Control
surfaces are typically rigid structures which maintain their shape
throughout rotation. Therefore, gaps or abrupt changes occur at the
hinge area of a conventional control surface. This gap increases
the drag and lowers the efficiency of the control surface.
Additionally, as the control surfaces are rotated, gaps are formed
between the ends of the hinged control surface and the adjacent
portions of the fixed wing.
U.S. Pat. No. 5,222,699, issued on Jun. 29, 1993, to Albach, et
al., and assigned to the assignee of the present invention
discloses a variable control aircraft control surface. This patent
discloses the use of an elastomeric transition section between
inboard and outboard edges of a variable contour control surface
and a main wing portion. The transition sections include thick
elastomeric layers with oversized holes therein and rods positioned
in the oversized holes. Some of the rods are attached to the main
wing portion while others-of the rods are attached to the control
surface.
Several wing structures have been designed which provide for
variable camber in an attempt to eliminate the need for separate
and distinct control surfaces located at the trailing edge of the
wing, which in turn would eliminate the abrupt changes or gaps
between the separate control surfaces and the trailing edge of the
wing. For example, U.S. Pat. No. 2,979,287 to Ross discloses an
inflatable wing with variable camber. The design incorporates an
inflatable fabric airfoil having upper and lower surfaces tied
together by a plurality of tie threads. The flexible fabric forming
the body of the wing is made so that the warp cords extend
lengthwise or longitudinally of the wing, with the weft cords
extending transversely of the wing. The weft cords are made more
elastic or resilient than the warp cords so that by varying the
inflation pressure inside the wing, the camber of the wing can be
changed together with the effective lift-drag ratio.
U.S. Pat. No. 3,118,639 to Kiceniuk discloses a control and
propulsion fluid foil. This design provides a foil construction
which utilizes fluid pressure applied within cells contained in the
foil construction in a manner to cause the foil to warp. This
warping changes the amount of lift force acting on the foil,
permitting it to function as a control surface. The application of
the variable pressures to a series of cells can also produce an
undulating motion. This undulation can function as a propulsion
means if the foil were used underwater.
An example of a unique wing reinforcement structure is seen in U.S.
Pat. No. 2,973,170 to Rodman which provides lightweight
reinforcement on the inner surface of the wing and a smooth
porcelainized outer wing surface. The reinforcement comprises a
network of crossed wires or rods of relatively small diameter.
Where the rods cross one another, the cross rods are flattened
against the wing so that the reinforcement is in contact with the
wing substantially up to the intersection of the wires or rods.
A need exists for an improved aircraft wing structure providing a
control surface that allows for variable camber of the wing while
eliminating any gap or abrupt change between the trailing edge of
the wing and the joining edges of the control surface. Such a
device should also provide an uninterrupted upper boundary wing
surface and be durable enough to withstand the conditions
encountered during flight.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, an aircraft
wing assembly is provided which includes a main wing portion having
a top skin and a bottom skin. A fixed contour control surface
having a top skin and a bottom skin and a forward end and a
trailing edge is attached at the forward end to the main wing
portion for movement between the fixed contour control surface and
the main wing portion. Upper and lower elastomeric layers join the
top and bottom skins, respectively, of the fixed contour control
surface to the corresponding top and bottom skins of the main wing
portion at the forward end.
In accordance with another aspect of the present invention, the
elastomeric layers are formed of elastomeric material having a
plurality of holes formed therethrough and a plurality of rods.
Each rod extends through one of the plurality of holes. Selected
ones of the rods are secured to the main wing portion while others
of said rods are connected to the variable control surface.
In accordance with another aspect of the present invention, the
elastomeric layers further include a main wing portion attachment
element and a fixed contour control surface attachment element, the
plurality of rods attached to one or the other of said attachment
elements, the main wing portion attachment element rigidly secured
to the main wing portion and the fixed contour control surface
attachment element rigidly secured to the fixed contour control
surface. In accordance with another aspect of the present
invention, the plurality of rods extend generally transverse the
axis of motion of the fixed contour control surface relative to the
main wing portion. In accordance with another aspect of the present
invention, the rods are formed of a material selected from the
group consisting of fiberglass, graphite, steel and aluminum. In
accordance with another aspect of the present invention, the
elastomeric material is silicon rubber.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, and for
further details and advantages thereof, reference is now made to
the following Detailed Description taken in conjunction with the
accompanying drawings in which:
FIG. 1a is a plan form view of the aircraft control surface on the
wing of an airplane;
FIG. 1b is a perspective view of an example of an aircraft control
surface in the form of a hinged control surface in accordance with
the prior art;
FIG. 1c is a perspective view of an aircraft control surface in the
form of a rigid control surface with transition sections in
accordance with the present invention;
FIG. 2 is a perspective view of an aircraft control surface in the
form of a rigid control surface with only one transition section
and hinge-line seal extending to the outboard end of the wing;
FIG. 3 is a perspective view of a transition section of an aircraft
control surface of the present invention;
FIG. 4a is a perspective view of the corner intersection between
the transition section and hinge-line encompassing both span wise
and chord wise support rods;
FIG. 4b is a side view of the corner;
FIG. 4c is a cross-section through the transition section;
FIGS. 5a and 5b are cross-sectional views of a second embodiment of
the present invention illustrating an elastomeric transition
section between the hinge connection of a main wing portion and a
fixed contour control surface; and
FIG. 6 is a perspective view of an elastomeric transition section
constructed in accordance with the teachings of the present
invention.
DETAILED DESCRIPTION
The present invention is directed to an aircraft wing structural
design having an integrated control surface that overcomes many of
the disadvantages found in the prior art. Referring to FIG. 1a, an
aircraft 10 is shown to illustrate the location of control surfaces
on wing 12, including a control surface 12a on the trailing portion
of wing 12. FIG. 1b is an enlargement of a portion of wing 12
wherein the control surface 12a is in the form of a prior art
embodiment of a hinged control surface 20. The control surface 20
is hinged at hinge line 24 to wing 12. Gaps 22 exist between the
outboard and inboard ends of control surface 20 and the stationary
wing 12 as the control surface 20 is moved. Further, a
discontinuity exists at hinge line 24.
Referring to FIG. 1c, which is an enlargement of a portion of a
wing 100 wherein the aircraft control surface 12a is in the form of
a rigid control surface 30 with transition sections in accordance
with an embodiment of the present invention, the control surface 30
incorporates a rigid control surface 102 and a transition section
30b between each end of the control surface 102 and the laterally
adjacent portion of wing 100. The control surface 102 can be moved
relative wing 100 by an actuator mounted between the wing 100 and
control surface 102. The actuator used can be either electrical or
hydraulic, linear or rotary with appropriate attachment to the
control surface 102 to allow movement in rotation about the
hinge-line.
FIG. 3 provides a sectional view of the transition section 30b. The
transition sections are located between the outboard and inboard
ends of the rigid contour control surface 102 and the fixed wing
100. Air loads on the transition section 30b are supported by
transfer structural rods 40 which are provided span wise. The rods
are positioned in oversized holes in upper and lower thick
elastomeric layers or skins 42 and 44, thereby creating a
semi-rigid structure. A flexible rib structure 43 ties upper and
lower skins 42 and 44 together so they are in unison and airloads
on both surfaces are shared.
Span wise structural rods 40 are socketed (i.e., rigidly attached)
at their ends either to the rigid control surface 102 or the fixed
wing 100. These span wise structural rods 40 extend over the width
of the transition section and are designed to slide in the
oversized holes in the transition section 30b as its length
increases to form the complex "S" shape. Thus, the span wise
structural rods 40 attached to the end of the contour control
surface 102 adjacent the fixed wing 100 overlap the rods 40
attached to the contour control surface 102 in parallel
relationship.
Thus, it can be seen that the present invention provides an
aircraft control surface designed to eliminate the discontinuities
that occur at the ends of the surface. The structure achieves a
more efficient airflow, and thus provides lower drag, by avoiding
the abrupt changes in the air flow direction which normally occurs
with hinged control surfaces. By avoiding abrupt changes which can
result in early separation of the air flow, and earlier onset of
transonic flow over the surface with the hinged control surface,
the present structure provides substantial aerodynamic
improvements. The structure is suitable for all hinged aerodynamic
control surfaces and the transition section is suitable for all
moving control surfaces.
The structure is achieved by use of a rigid airfoil shape with
hinge-line transition sections to eliminate the gaps and abrupt
changes that occur at the hinge area of a conventional control
surface, and an elastomeric transition sections at the ends to
provide a smooth transition between the deflected and the
undeflected shape of the fixed wing or tail surface section. The
elastomeric transition section is designed to assume a complex "S"
shape required to provide a smooth transition between the deflected
control surface and the adjacent fixed wing. The elastomeric
transition section may also be used individually to provide a
continuous surface between the fuselage and any moving mixed
contour control surface.
With reference now to FIGS. 1c, 2, 4a, 4b, 5 and 6, a second
embodiment of the present invention is illustrated. FIGS. 5a and 5b
illustrate a portion of a wing 100 and a control surface 102 hinged
at its forward end 104 by hinge 106 to the wing 100. The control
surface 102 pivots about axis 108 of the hinge 106 under the action
of hydraulic actuators of the type commonly used in aircraft
construction. The actuators can also be screw actuators, electric
actuators or rotary a actuators.
Secured between the top surface 116 of the wing 100 and the top
surface 114 of the control surface 102 is an elastomeric transition
section 118. Similarly, between the bottom surface 120 of the wing
100 and bottom surface 122 of the control surface 102 is an
elastomeric transition section 124.
FIG. 3 shows the control surface 102 can extend to the outboard end
of the wing where the control surface tapers to a line. The
transition sections 118 and 124 merge in a smooth transition as the
control surface tapers to the outboard end to form a single
thickness.
With reference to FIG. 6, the elastomeric transition sections 118
and 124 are seen to include an elastomeric material 126 having a
plurality of elongate holes 128 formed therethrough. A wing
attachment element 130 is attached at one end of the elastomeric
material while a control surface attachment element 132 is attached
at the other end of the elastomeric material 126. A plurality of
wing mounted rods 134 are rigidly secured to the element 130 and
extend within selected ones of the holes 128 toward and possibly
through the control surface attachment element 132. Similar control
surface rods 136 are rigidly secured to the control surface
attachment element 132 and extend through others of the holes 128
toward and possibly through the wing attachment element 130. The
attachment elements 130 and 132 each have bolt holes to bolt the
elements rigidly to the wing 100 and control surface 102,
respectively.
In a manner similar to that described above, the elastomeric
transition sections 118 and 124 can expand and contract as the
control surface 102 is activated relative to the wing 100 while
maintaining a smooth aerodynamic transition between the wing and
control surface. The elastomeric transition sections 118 and 124
can also be used in conjunction with the transition sections 30b
previously described between the inboard and outboard edges of the
control surface and the adjacent wing structure.
The rods can be formed of any suitable material, including
fiberglass, graphite, steel and aluminum. Fiberglass rods can be
formed as pultruded material of astroquartz epoxy or S2 glass epoxy
fiber. It is desirable to have a high strength to modulus of
elasticity ratio. The elastomeric material can be any suitable
material, such as room temperature vulcanizing silicon rubber as
sold by Dow Corning as, for example, Dow Corning 6121
elastomer.
With reference to FIGS. 4a and 4b, there is illustrated corner 140
which forms the transition between elastomeric transition section
118 and the layer 42 of transition section 30b at the ends of the
control surface. As seen in FIG. 4c, the transition between section
124 and layer 44 is essentially identical. In section 30b, rods 40
extend span wise in elastomeric layers 42 and 44. Near the hinge
106, reduced diameter span wise rods 107 extend span wise between
the inboard and outboard ends of the control surface in elastomeric
layer 108 which is integrally formed with elastomeric layer 112
having reduced diameter fore and aft rods 110 therein. The rods 110
are all secured at their forward ends to the wing 100. Alternate
rods 40 and 107 are connected to the control surface 102 and the
outboard or inboard edges of the wing 100. Rods 110 are allowed to
slide fore and aft in oversized holes 111 in elastomeric layer 112.
Corner 140 thus forms a smooth transition between the hinging
action about the hinge 106 and the movement necessary between the
inboard and outboard edges of the control surface and the facing
surfaces of the wing.
Although preferred embodiments within the invention have been
described in the foregoing description and illustrated in the
accompanying drawings, it will be understood that the invention is
not limited to the embodiments disclosed, but is capable of
numerous rearrangements, modifications, substitution of parts and
elements without departing from the spirit of the invention.
Accordingly, the present invention is intended to encompass such
rearrangements, modifications and substitutions of parts and
elements as followed in spirit and scope of the invention.
* * * * *